152 APPLIED BIOLOGY 



Buckwheat Seed. Compare with the four-o'clock. 



Morning Glory. Embryo with two cotyledons is embedded in 

 the endosperm. Epicotyl not apparent until germination. 



Seeds of Oak (acorn), Horse-Chestnut, Windsor- or Horse-Bean, 

 and Lupines. Compare with the pea seed, especially behavior in 

 germination. 



Peanut. A nut-like pod, comparable to pod of the closely re- 

 lated bean. 



Onion Seed. Embryo is embedded in endosperm. Peculiar 

 in that the one cotyledon lengthens in germination and raises the 

 seed-coat with endosperm out of the ground. When endosperm 

 is all absorbed cotyledon withers at top and epicotyl appears 

 near the surface of soil. Compare with germination of the corn 

 grain. 



Wheat and Oats. Germinate on moist paper and in soil, and 

 compare with corn. 



141. Number of Cotyledons in Seeds. Some of the seeds 

 studied have one and some two cotyledons. This difference 

 in number has been made the basis of classification of a large 

 number of the flowering or seed-plants into the monocoty- 

 ledons (one cotyledon) and dicotyledons (two cotyledons). 

 In addition to the number of cotyledons, plants of these 

 two groups are marked by certain characteristics of stems 

 and leaves and flowers which will be described later (161 and 

 197). Among the monocotyledons are all true grasses 

 such as timothy, June-grass, lawn-grasses and all the lilies, 

 tulips, daffodils, iris, orchids, banana-plants, trillium, pine- 

 apple, palms, etc. Among the dicotyledons are the familiar 

 trees of our deciduous forests, the fruit-bearing trees and 

 shrubs of our orchards and gardens, all our most common 

 garden vegetables (except onions and asparagus), and most of 

 the common wild flowers which do not resemble lilies in leaves 

 and flowers. 



Many of the common cone-bearing evergreen trees (pine, 

 yew, fir, cypress, hemlock, etc.) have seeds with more than 

 two cotyledons (from 3 to 15). The cone-like flowers (as 

 well as other parts) of such plants are different from the 



